Orthopaedic surgeons in the United States continue to seek improved therapies for the 600,000 fractures that suffer from delayed healing and the 100,000 that become nonunions. Infected nonunions remain a challenge and frequently require staged treatment protocols. The first step is removal of infected hardware, surgical debridement and placement of solid carriers preloaded with eluents (e.g. antibiotic “beads”). The second step involves systemic intravenous delivery of antibiotics. Finally, the patient undergoes a second surgical procedure for possible removal of solid carriers, definitive surgical stabilization and local delivery of therapeutics (e.g. recombinant human-Bone Morphogenetic Protein-2) and bone graft during surgery.
Current treatments face multiple challenges and are invasive. They involve repeated surgical approaches and are limited by the inability to modify the therapeutics after implantation (e.g. if the cultures show resistant organisms). Systemic administration of antibiotics is problematic secondary to the need for high blood levels to achieve therapeutic levels in the fracture environment. The side effects of these high serum levels require close monitoring to avoid major complications. This is an issue that would benefit from improved drug delivery methods.
This is far from the only issue faced by surgeons when it comes to delivery of therapies. Other problems include systemic intravenous delivery (e.g. chemotherapeutic agents for cancer or intravenous pain medications), local delivery of therapeutics at the time of surgery (e.g. recombinant human-Bone Morphogenetic Protein-2 after spine fusion), and direct injection to a joint (e.g. corticosteroid injection to a knee for osteoarthritis management). These issues would benefit from improved delivery of therapeutics, namely antibiotics, anti-inflammatory pain medications, bone healing modulators and chemotherapeutic agents. What is needed is a method of targeted delivery of the therapeutic or diagnostic agent to concentrate the agent at the site of need, thus lowering the overall dose of the therapeutic or diagnostic agent administered to the patient. Surprisingly, the present invention meets this and other needs.